Thought your pet snail was cool? Well, unless yours has developed eyes that shoot lasers or the ability to speak, then it’s probably not as cool as the aptly named Scaly-Foot Snail, which has its very own metal armour.
These snails have evolved shells made of iron, as well as a foot covered with iron plates. This appears to be down to bacteria which is helping facilitate the production of the iron sulfides that make up the shell and plates. It is thought that no other animal on Earth can utilize iron this way.
However, the shells aren’t totally rigid like a standard snail’s. They are flexible but strong, sort of like chain-mail. This is down to the three layers that make up the shell: The iron-plated top layer, the calcified bottom layer and a thick organic layer in between. The iron provides protection from predators, while the fleshy part in the middle acts as a shock-absorber.
The scales on the foot serve a similar purpose – to protect them from predators, such as other snails who hunt by firing harpoons into the flesh of fish and snails and injecting a venom. It’s thought that the iron plating of the scaly-foot snail deflects these missiles, like a knight’s armour deflecting a lance.
One species of underwater snail – Cone snails – are well known for their poisonous venom, and more than fifteen people have been killed because of it. That’s scary enough, but scientists have recently found that one particular of these snails – Conus geographus (The Geography Cone Snail) – doesn’t even need to release its venom.
Usually, to fill your prey with poison you’d need a claw, fang, or stinger, and the geography cone snail does have a tooth that it can use to inject venom into animals, but it can also just release venom straight into the water. The cocktail of toxins disorients the surrounding fish, enabling the snail to simply swallow them up.
The venom was found to be a more compact form of insulin than the kind humans and vertebrates use, which when injected into a fish, causes a fast and dangerous drop in blood glucose levels, usually called hypoglycemia, which stopped them from being able to swim properly. The researchers estimate that the snail could, if it wanted to, take out a whole school of fish with this insulin venom.